Synchronisation of supply and demand is necessary to increase efficiency of nutrient use in soilless horticulture

Abstract

In modern horticulture on artificial substrates effective systems for plant nutrition have been developed for many crops. The efficiency of nutrient use, however, is often low: on average 40 to 80% of all nutrients applied to tomato and cucumber grown on rockwool slabs is leached from the root environment. In soilless systems only the volume of nutrient solution provides buffering for nutrients when supply and uptake of nutrients are not equal. From a simple model of water and nutrient balance for a well-mixed nutrient solution system, relations between nutrient and water leaching were derived, explaining the low nutrient use efficiencies obtained in practice on soilless media. Improvement of nutrient use efficiency largely depends on improving synchronisation of nutrient supply with nutrient demand. The ratio of “uptake concentration” (current nutrient uptake rate divided by current water uptake rate) and the nutrient concentration in the system is a key parameter. Understanding of fluctuations in this ratio, as determined by daily rhythms, weather conditions and growth stages, may lead to intensive plant nutrition systems that are not only effective, but also efficient.